1. Field of the Invention
The present invention relates to a timing recovery device, especially to a multi-channel timing recovery device.
2. Description of Related Art
A conventional multi-channel timing recovery configuration includes a plurality of timing recovery circuits, each of which corresponds to a data channel. In an application without any additional clock channel, each of the said timing recovery circuits generates a sampling clock exclusively for itself according to the signal from its corresponding data channel, which means that each timing recovery circuit here should be an independent and intact timing recovery circuit, and thus the whole circuit area, power consumption and cost climb up obviously. On the other hand, in an application with a clock channel, a reference clock is transmitted through the clock channel, and then a common phase locked loop is used to provide an in-phase signal and a quadrature-phase signal for each of the timing recovery circuits according to the reference clock (as it is described in the US patent with U.S. Pat. No. 7,158,587). As a result, each timing recovery circuit can generate its sampling clock according to the signal from its corresponding data channel and the said in-phase and quadrature-phase signals. Although the latter case doesn't require multiple sets of phase locked loops, it is only applicable to a system with a clock channel.
People who are interested in the prior art may refer to the following documents:
(1) Behzad Razavi “Design of integrated circuits for optical communications” Boston: McGraw-Hill, c2003. pp. 306-309.
(2) Guanghua Shu, Saurabh Saxena, Woo-Seok Choi, Mrunmay Talegaonkar, Rajesh Inti, Amr Elshazly, Brian Young and Pavan Kumar Hanumolu, “A Reference-Less Clock and Data Recovery Circuit Using Phase-Rotating Phase-Locked Loop,” IEEE J. Solid-State Circuits, vol. 49, no. 4, pp. 1036-1047, April. 2014.(3) US patent with U.S. Pat. No. 7,158,587.(4) US patent with U.S. Pat. No. 6,204,705.(5) US patent application with publication number 2011/0286562.